I thought RFA could sign for more with their own team... please clarify... is that just UFA?

Unrestricted free agents are free agents who can sign immediately and..For a certain amount of money.
Restricted Free agents like Smith and Iggy still have ownership to their teams after their contracts end. You can sign an offer sheet for them and the original team of the player can match the offer given a time span of 7 days. If not matched, the player is gone.
I know there are more specifics but I don't know them. Care to fill me in?